We report on dynamic covalent polymers derived from elemental sulfur that can be used as thermally healable optical polymers for mid-IR thermal imaging applications. By accessing dynamic S−S bonds in these sulfur copolymers, surface scratches and defects of free-standing films of poly(sulfur-random-1,3-diisopropenylbenzene) (poly(S-r-DIB) can be thermally healed, which enables damaged lenses and windows from these materials to be reprocessed to recover their IR imaging performance. Correlation of the mechanical properties of these sulfur copolymers with different curing methods provided insights to reprocess damaged samples of these materials. Mid-IR thermal imaging experiments with windows before and after healing of surface defects demonstrated successful application of these materials to create a new class of "scratch and heal" optical polymers. The use of dynamic covalent polymers as healable materials for IR applications offers a unique advantage over the current state of the art (e.g., germanium or chalcogenide glasses) due to both the dynamic character and useful optical properties of S−S bonds.T he development of stimuli-responsive polymers has been recently investigated as a means to healable materials. 1 While a number of functional groups have been utilized to create dynamic covalent polymers, these typically require that the dynamic functional groups are orthogonal to the polymer forming reaction. 2−5 However, disulfide and polysulfide bonds are a class of dynamic covalent functional groups that can be installed via the polymer forming reaction by direct (co)-polymerization with elemental sulfur (S 8 ) or di/polysulfides. 6−8 The early work by Tobolsky et al. on polyurethane copolymer networks demonstrated the stress-relaxation properties imparted via the inclusion of di-and tetrasulfide bonds. 9−11 More recently, Rowan et al. reported the preparation of polymeric disulfide networks via oxidative polymerizations of di-and tetrasulfide comonomers to create self-healing films and shape memory materials. 12 We recently reported on the synthesis of dynamic covalent polymers via the inverse vulcanization of S 8 and 1,3-diisopropenylbenzene (DIB), enabling the generation of the first dynamic covalent polymers with composed primarily of dynamic bonds. In this system, the dynamic behavior in high sulfur content copolymers was directly controlled by the comonomer feed ratios and copolymer composition, demonstrating that such properties were modulated by altering sulfur rank (number of S−S bonds) within these materials. 13 To date, numerous applications of dynamic covalent polymers have been explored, with an emphasis on the creation of stimuli-responsive macromolecules and self-healing materials. 5,14,15 In these materials, the primary function of the dynamic covalent bonds served to enable reversible bond scission, or reorganization within the macromolecular framework. However, there remains opportunities to create dynamic covalent polymeric materials that exhibit multiple functions in addition to those relat...

6. Dynamic rheological frequency analysis of poly(sulfur-r-1,3diisopropenylbenzene) (poly(S-r-DIB)) and poly(sulfur-r-1,3,5triisopropenylbenzene) (poly(S-r-TIB)) copolymers 7. Dynamic mechanical Analysis of of poly(sulfur-r-1,3diisopropenylbenzene) (poly(S-r-DIB)) and poly(sulfur-r-1,3,5triisopropenylbenzene) (poly(S-r-TIB)) copolymers 8. Time resolved rheological analysis of self-healing properties of poly(sulfur-r-1,3-diisopropenylbenzene) (poly(S-r-DIB)) and poly(sulfur-r-1,3,5-triisopropenylbenzene) (poly(S-r-TIB)) 9. Mechanical analysis of poly(sulfur-r-1,3-diisopropenylbenzene) (poly(S-r-DIB)) and poly(sulfur-r-1,3,5-triisopropenylbenzene) (poly(S-r-TIB)) copolymers 10. Plot of refractive Index as a function of wavelength for poly(sulfur-r-1,3,5-triisopropenylbenzene) (poly(S-r-TIB)) copolymers 11. FTIR and UV-Vis transmission plots of poly(sulfur-r-1,3,5triisopropenylbenzene) (poly(S-r-TIB)) copolymers 12. Differential scanning calorimetry (DSC) analysis of poly(sulfur-r-1,3diisopropenylbenzene) (poly(S-r-DIB)) and poly(sulfur-r-1,3,5triisopropenylbenzene) (poly(S-r-TIB)) copolymers 13. Thermogravimetric analysis (TGA) of poly(sulfur-r-1,3,5triisopropenylbenzene) (poly(S-r-TIB)) and poly(sulfur-r-1,3diisopropenylbenzene) (poly(S-r-DIB))copolymers II) Results and Discussion Section A. Dynamic rheological frequency analysis of poly(sulfur-r-1,3diisopropenylbenzene) (poly(S-r-DIB)) and poly(sulfur-r-1,3,5triisopropenylbenzene) (poly(S-r-TIB)) copolymers to determine degree of crosslinked network microstructures B. Time resolved rheological analysis of self-healing properties of poly(sulfur-r-1,3-diisopropenylbenzene) (poly(S-r-DIB)) and poly(sulfur-r-1,3,5-triisopropenylbenzene) (poly(S-r-TIB)) copolymers C. Powder X-Ray Diffraction (XRD) of poly(sulfur-r-TIB) copolymers

High sulfur content copolymers were prepared via inverse vulcanization of sulfur with 1,4-diphenylbutadiyne (DiPhDY) for use as the active cathode material in lithium-sulfur batteries. These sulfur-rich polymers exhibited excellent capacity retention (800 mA h g À1 at 300 cycles) and extended battery lifetimes of over 850 cycles at C/5 rate. Fig. 3 (a) Cycling performance at C/5 of Li-S battery fabricated with poly(S-co-DiPhDY) prepared with a 10 wt% DiPhDY, 90 wt% sulfur feed ratio. (b) Plot of potential versus charge/discharge capacity for the Li-S cell shown in (a) at 100 cycle intervals. (c) Charge/discharge rate performance of Li-S battery with poly(S-co-DiPhDY) (10 wt% DiPhDY) at various current densities (1 C ¼ 1672 mA h). All capacities are specific capacity based on sulfur loading.This journal is

We report on the preparation of ultrahigh refractive index polymers via the inverse vulcanization of elemental sulfur, selenium, and 1,3-diisopropenylbenzene for use as novel transmissive materials for mid-infrared (IR) imaging applications. Poly(sulfur-random-selenium-random-(1,3-diisopropenylbenzene)) (poly(S-r-Se-r-DIB) terpolymer materials from this process exhibit the highest refractive index of any synthetic polymer (n > 2.0) and excellent IR transparency, which can be directly tuned by terpolymer composition. Sulfur or selenium containing (co)polymers prepared via inverse vulcanization can be described as Chalcogenide Hybrid Inorganic/Organic Polymers (CHIPs) and are polymeric analogues to wholly inorganic Chalcogenide Glasses (ChGs), which are commonly used as transmissive materials in mid-IR imaging. Finally, we demonstrate that CHIPs composed of (poly(S-r-Se-r-DIB) can be melt processed into windows that enabled high quality mid-IR thermal imaging of human subjects and highly resolved imaging of human vasculature.